AT least four people have been hit by gunfire in a classroom shooting at a Southern California primary school, police and fire officials say.

San Bernardino Police Chief Jarrod Burguan said the shooting at Northpark Elementary School in San Bernardino, east of Los Angeles, on Monday was initially believed to be a "murder-suicide" and that two students had been taken to the hospital for treatment.

We believe this to be a murder suicide. Happened in a class room. Two students have been transported to the hospital.

He added that preliminary information was that there were four victims and that the "suspect is possibly down as well".

The San Bernardino County Fire Department said in a Twitter post that there were "multiple gunshot victims" from the incident.

A spokeswoman for San Bernardino City Unified school district says one of four people shot in a classroom was a teacher.

In this frame from video provided by KABC-TV, faculty and students evacuate North Park School Elementary School as emergency personnel respond to a shooting inside on Monday, April 10, 2017, in San Bernardino, Calif.KABC-TV via AP

Maria Garcia says the shooting is believed to be a domestic dispute. At least two students have been flown to a hospital.

The other students in the school were evacuated and taken to a nearby school.